A micromechanical pressure sensor device is described in German Patent Application No. DE 10 2013 213 071 B3 which has an ASIC wafer (1a) having a front side and a rear side, a rewiring device having a plurality of stacked strip conductor levels and insulation layers, a MEMS wafer having a front side and a rear side, a first micromechanical functional layer formed above the front side of the MEMS wafer, a second micromechanical functional layer formed above the first micromechanical functional layer, a diaphragm area being developed in one of the first and second micromechanical layers as a deflectable first pressure detection electrode, on which pressure is applicable through a via in the MEMS wafer, a stationary second pressure detection electrode being developed at a distance and opposite from the diaphragm area in the other of the first and second micromechanical functional layer, the second micromechanical layer being connected via a bond connection to the rewiring device in such a way that the stationary second pressure detection electrode is enclosed in a cavity, the diaphragm area being formed in first micromechanical functional layer (3) and the stationary second pressure detection electrode being formed in the second micromechanical functional layer, and the stationary second pressure detection electrode having an anchoring area, which is anchored on the first micromechanical functional layer.
A similar micromechanical pressure sensor device is described in U.S. Patent Application Publication No. 2012/0043627 A1, a cap substrate being used instead of the ASIC wafer for capping.
Although any micromechanical components are applicable, the present invention and its underlying object to be achieved are explained with reference to components based on silicon.
Micromechanical sensor devices for measuring acceleration, rotation rate, magnetic field, and pressure, for example, are generally available, and are mass-produced for various applications in the automotive and consumer sectors. In particular the miniaturization of components, functional integration, and effective cost reduction are trends in consumer electronics.
Nowadays, acceleration sensors and rotation rate sensors, as well as acceleration sensors and magnetic field sensors, are already manufactured as combination sensors (6d), and in addition there are first 9d modules, in which in each case 3-axis acceleration sensors, rotation rate sensors, and magnetic field sensors are combined into a single sensor device.
In contrast, pressure sensors nowadays are developed and manufactured separately from the above-mentioned 6d and 9d modules. An important reason for this is the necessary media access which a pressure sensor requires, as opposed to inertial sensors and magnetic sensors, which greatly increases the effort and the costs for packaging the pressure sensor. Other reasons for the separation of pressure sensors are the different MEMS manufacturing processes and the different evaluation processes.
For example, pressure sensors often make use of piezoresistive resistors for the evaluation, whereas inertial sensors are preferably evaluated capacitively.
However, sensor devices which are able to measure the pressure in addition to inertial variables may represent an interesting expansion of the options for functional integration, in particular in the area of consumer electronics. Such integrated 7d modules, or, for integration of a 3-axis magnetic sensor, 10d modules, could be used for navigation applications (indoor navigation), for example. The functional integration is promising for achieving cost reductions as well as reduced space requirements on the application circuit board.
Methods of so-called vertical integration, hybrid integration, or 3D integration are described, for example, in U.S. Pat. Nos. 7,250,353 B2 and 7,442,570 B2, in which at least one MEMS wafer and one evaluation ASIC wafer are mechanically and electrically connected to one another by way of wafer bonding processes. These vertical integration methods are particularly attractive in combination with silicon vias and flip chip technologies, as a result of which the external contacting may take place as a bare die module or a chip scale package, and thus without plastic outer packaging, as described in U.S. Patent Application Publication Nos. 2012/0049299 A1 and US 2012/0235251 A1, for example.
U.S. Patent Application Publication No. 2013/0001710 A1 describes a method and a system for forming a MEMS sensor device, in which a handling wafer is bonded to a MEMS wafer by way of a dielectric layer. After structuring the MEMS wafer to form the micromechanical sensor device, a CMOS wafer is bonded to the MEMS wafer, which includes the sensor device. At the end of the process, the handling wafer may be further processed by etching or back-grinding, if necessary.